Estimating Transit Queue Volume Using Probe Ratios

1. A method of estimating transit volume in an area, the method involving a device having a processor and comprising: executing, on the processor, instructions that cause the device to: monitor a probe speed of respective probes in the area to detect a transit queue; from the probe speeds of the probes: estimate a queue length change of the transit queue; estimate a probe rate change of probes in the transit queue; from the queue length change and the probe rate change, identify a probe ratio among travelers of the transit queue; and using a count of the probes and the probe ratio, identify the transit volume of the transit queue.

2. The method of claim 1 , wherein executing the instructions further causes the device to, according to the probe speed of the respective probes in the area: identify a start location of the transit queue in the area; and identify an end location the transit queue in the area.

3. The method of claim 1 , wherein estimating the queue length change further comprises: estimating a geographic length of the queue; estimating an average traveler length of travelers in the transit queue; and dividing the geographic length of the queue by the average traveler length.

4. The method of claim 3 , wherein estimating the average traveler length further comprises: estimating an average probe speed of travelers in the transit queue; and estimating the average traveler length proportionally with the average probe speed of travelers in the transit queue.

5. The method of claim 1 , wherein executing the instructions further causes the device to identify, according to the probe speed of the respective probes in the area: an ingress of the probe to the transit queue indicated by a reduction in the probe speed below a typical probe speed for the area; and an egress of the probe from the transit queue indicated by a restoration of the typical probe speed for the area.

6. The method of claim 1 , wherein: executing the instructions further causes the device to: partition the area into at least two segments, and associate a probe location of the respective probes with a selected segment of the at least two segments of the area; and identifying the transit volume further comprises: for a selected segment, identifying the transit volume of the transit queue for the selected segment using the count of the probes associated with the selected segment.

7. The method of claim 6 , wherein: the area comprises a path having at least two lanes; and partitioning the area further comprises: partitioning the path into at least two segments respectively representing one of the at least two lanes.

8. The method of claim 6 , wherein partitioning the area further comprises: partitioning the area into: a first segment including a first subset of probes reporting a first average probe speed; and a second segment including a second subset of probes reporting a second average probe speed that is different from the first average probe speed of the first segment.

9. The method of claim 6 , wherein partitioning the area further comprises: partitioning the area into: a first segment representing a first transit area type; and a second segment representing a second transit area type that is different from the first transit area type of the first segment.

10. The method of claim 6 , wherein: the area further comprises at least two ingress points and at least two egress points; and partitioning the area further comprises: partitioning the area into segments respectively representing a span of the area between a selected ingress point and a selected egress point.

11. A server that estimates a transit volume in an area having, the server comprising: a processor; a probe communicator that receives, from respective probes in the area, a report of a probe speed; and a memory storing instructions that, when executed by the processor, provide a system comprising: a transit queue detector that, from the probe speeds of the probes, identifies a transit queue; a transit queue modeler that, from the probe speeds of the probes: estimates a queue length change of the transit queue; estimates a probe rate change of probes in the transit queue; and a transit volume estimator that: from the queue length change and the probe rate change, identifies a probe ratio among travelers of the transit queue; and using a count of the probes and the probe ratio, identifies the transit volume of the transit queue.

12. The server of claim 11 , wherein identifying the transit volume further comprises: identifying a probe ratio for each of at least two transit queues in an area; and averaging the probe ratios for the at last two transit queues to identify a regional probe ratio for the area.

13. The server of claim 11 , wherein the transit queue modeler further estimates a queue length change rate of the queue length of the transit queue.

14. The server of claim 11 , wherein the transit queue modeler further estimates a queue duration of the transit queue.

15. The server of claim 11 , wherein the transit queue modeler further estimates a queue severity of the transit queue according to a probe speed differential between an average probe speed of the probes and a typical probe speed for travelers in the area.

16. The server of claim 11 , wherein: respective transit queues are associated with a queue type selected from a queue type set; and the transit queue modeler further classifies the transit queue as a queue type selected from the queue type set.

17. A nontransitory computer-readable medium storing instructions that, when executed by a processor of a device, cause the device to estimate a transit volume of a transit queue in an area, by: monitoring a probe speed of respective probes in the area to detect a transit queue; from the probe speeds of the probes: estimating a queue length change of the transit queue; estimating a probe rate change of probes in the transit queue; from the queue length change and the probe rate change, identifying a probe ratio among travelers of the transit queue; and using a count of the probes and the probe ratio, identifying the transit volume of the transit queue.

18. The nontransitory computer-readable medium of claim 17 , wherein: a user of a selected traveler is associated with a route through the area to a destination, and having a destination arrival estimate; and executing the instructions further causes the device to notify the user of the transit queue in the area.

19. The nontransitory computer-readable medium of claim 18 , wherein executing the instructions further causes the device to: identify an alternative route to the destination that avoids the transit queue; and notify the user of the alternative route to the destination.

20. The nontransitory computer-readable medium of claim 18 , wherein: the route of the user is associated with a destination arrival estimate; and executing the instructions further causes the device to: identify an adjusted destination arrival estimate according to the queue length change of the transit queue; and notify the user of the adjusted destination arrival estimate.